Tracer Pulse Dynamic Flow and Chemistry Profile for Well Characterization

The Tracer Pulse Dynamic Flow Meter (TPDF) - consists of injecting small volumes (20 ml to 60 ml) of rhodamine dye (FWT 50) along vertically spaced centers within a production, injection, ASR, monitoring well or borehole. The dye is NSF 60 Approved for use in potable drinking water wells.

Release of the dye is controlled by an electro-pneumatic injection process where the energy from a pneumatic load is converted to a hydraulic load inside the injection tubing which contains the dye.

When the hydraulic load inside the dye tube exceeds the spring force inside the injection nozzle, a small quantity of dye is released into the surrounding well water. The same process is repeated at each injection depth.

The time (T0) is marked for each injection and the peak return (PR) time of the dye to a ground surface based fluorometer (TPR) is marked as well. Knowing the travel time for each dye peak return and knowing the depth-distance between each pair of consecutive injection points allows a flow velocity (d/t) to be calculated between each pair of injection points.

Cumulative flow (Qn) is then calculated by multiplying the flow velocity (Vn) by the cross sectional surface area (An) of the well at each vertical injection point.

Where cumulative flow is defined as,

(1) Qn = (Dn-Dn)/(Tn-Tn) πr2

Therefore,

(2) Qn = Vn x An

Incremental flow is defined by sequentially subtracting each cumulative flow from the next

(3) Q1-Q2, Q2-Q3, Q3-Q4, Qn-Qn+1

Incremental flows are then plotted as a distinct contribution between each paired section of injection points along the well screen length.

Chemistry Profile

Assuming conservative mixing inside the well we can derive the average incremental chemical contributions from cumulative contributions between any two vertically-paired and consecutive water samples by using the following equation...

(4) Ca1 = (Q1C1-Q2C2)/(Q1-Q2)

where Ca1 is defined as the average incremental concentration between each pair of sequential and vertically spaced groundwater sampling points (C1 and C2) within the well. Q1 and Q2 are the sequentially derived cumulative flow measurements obtained from the same depths as C1 and C2, respectively. Carrying this step forward, we end up with a series of repetitive calculations for each depth measurement with a well, that being...

(5) Ca1 = (Q1C1-Q2C2)/(Q1-Q2)

Ca2 = (Q2C2-Q3C3)/(Q2-Q3)

Can = (QnCn-Qn+1Cn+1)/(Qn-Qn+1)

The algebraic method described in equations (4) and (5) is called flow weighting and is the essential step calculation by which we can extract incremental from cumulative chemical contribution along the well screen.

See sample report

Tracer Pulse Ambient Flow and Chemistry Profile For Well Characterization

The Tracer Pulse Ambient Flow Meter is a new technology (patent pending) developed by BESST, Inc. It consists of miniaturized underwater lasers that are fired in a wide-beam spread from fiber optic cable emitters at the submerged ends of the fiber optic cables.

A ground surface based control unit contains the laser, beam splitter, photon receivers, signal amplifiers, diopters that convert light signals to voltage as well as the laser output and return photonic input channels for the fiber optic cables. With military grade fiber optic cables, laser-beam transmission and photonic emission return to the signal processing unit (SPU). The laser beam wavelength is transmitted at a band width between 540 to 560 nanometers which is the specific spectral band that causes the Rhodamine Red FWT 50 tracer to fluoresce.

In order to use laser induced tracer fluorescence as a flow meter, the tracer pulse injection nozzle is placed equidistant between a minimum of two laser emission probes. The time setting for the injection is determined by well diameter and in-well flow velocity.

The dye is injected sideways (as with the Tracer Pulse Dynamic Flow Meter) and disperses quickly within the well groundwater column immediately surrounding the injection nozzle. The injection process used to force the dye from the injection nozzle is the same process that is used for the Tracer Pulse Dynamic Flow Meter (TPDF).

The purpose of said profiling is to determine pathways of water migration and mass transfer of undesirable chemicals and compounds through a well when the pump is turned off.

These data sets help us understand potential risks to the water quality of critical aquifer assets through the process of vertical and lateral mass transfer.